SPBAERTALES 



49 



13 Stroma fused with the substratum. 14. 



Stroma formed almost wholly of hardened fungal hyphae. 15. 



14. Conidia developed in pycnidia. Valsaceae. (logen.) 

 Conidia developed from a flattened surface. 



Melanconidaceae. (9 gen.) 



15. Spores small, cylindric, I -celled, mostly curved, hyaline or yellowish- 



brown. Diatrypaceae. (8 gen.) 



Spores rather large, i-many-celled, hyaline or brown ; conidia mostly 



in cavities of the stroma. Melagrammataceae. (9 gen.) 



Spores l-celled (rarely 2-celled), blackish brown ; conidia developed 



on the upper surface of the young stromata. 



Xylariaceae. ( 14 gen. ) 



It will become apparent in using the above synopsis that many 

 of the characters used to distinguish some of the families gradually 

 shade into each other. This arises in part from the existence of 

 numerous intermediate or connecting forms in this order, and in 

 part from our lack of positive information relative to many of the 

 genera. In the determination of genera it is sometimes simpler 

 to follow the artificial arrangement of Saccardo in whose Sylloge 

 Fitngoriun natural alliances are largely passed over and genera 

 are arranged according to their spore forms and colors. 



With the exception of the Xylariaceae most of the plants of the 

 entire order are comparatively inconspicuous. Besides the species 

 of Hypoxylon, noted above, the family Xylariaceae contains Dal- 

 dinia with three or four species which form blackish or brownish 

 masses, often as large as butternuts, of an ovoid or spherical form. 

 D. coticentrica shows a series of concentric brown layers within 

 the stroma, while D. vcrnicosa when young shows a similar series 

 of layers, the main portions of each being composed of whitish 

 • membranous septa. Both are comparatively common. Other 

 genera are Ustulma, which forms flattish, irregular, crust-like 

 masses growing commonly on maples ; Ntimnmlaria forms more 

 regular crust-like, smooth masses bursting through the young bark 

 of sapling oaks or sometimes occurs on the branches of larger 

 trees ; Xylaria forms simple or branching club-like masses grow- 

 ing on logs, or at the bases of trees or stumps attached to the wood 

 beneath the surface of the ground ; X. polymorpha {PI. 4. f. 11 , 

 12) is a common species often growing in large clusters ; Poronia 



4 



